UNL1MTD Posted June 10, 2007 Share Posted June 10, 2007 Well, my MJ decided that it wouldn't start up for me while I was at the dump. Got a jump from a Grand Cherokee (jeep people are good people, didn't even have to ask the guy, just nodded and popped his hood when he saw me) and drove it home (bout 10 mins). On the way to the dump the radio kept cutting out and the horn wasn't working all the time. When I got it home it wouldn't start again. There is some charge in the battery however as the lights come on and everything, just not enough for it to power the starter. I don't have full gauges, but the idiot light with the battery never came on at all and is not on. This sorta came out of no where, but maybe not. Over the last two days its been started 12 times atleast and 9 of those times it was on for less than 3 minutes (most under a minute) and driven no more than 200 feet. (moving mulch around the yard from one spot to another). So its seen a lot of starts. My MJ has a long crank period due to some kind of fuel delivery issue, so I think it takes a lot of charge away from the battery. So my questions- How long does an Alternator take to charge a battery? Are any of the above happenings a sign that my alternator is done? Do the 2.5L and 4.0L share the same alternator? Is having the aux horn wire just hanging out the right thing or does that need to be looped back into the circut some how? (this is the last change I made to the MJ, but that was 12 starts ago) I still got the parts MJ so I can steal that alternator if the parts swap. If not I'll just get a new on. I also have another battery to drop in that should have a full charge on it. Just looking for a little advice before I start on it. Thanks Link to comment Share on other sites More sharing options...
Pete M Posted June 10, 2007 Share Posted June 10, 2007 I would start by cleaning the terminals and checking the condition of the battery cables. Most of my electrical issues that looked like a battery or alternator problem was simply corrosion or poor contact. Link to comment Share on other sites More sharing options...
DirtyComanche Posted June 10, 2007 Share Posted June 10, 2007 What I want to know is how much you use the horn to be able to know it wasn't working all the time...? Link to comment Share on other sites More sharing options...
fiatslug87 Posted June 10, 2007 Share Posted June 10, 2007 Not exactly sure of answers to your questions, but once you get it started pull one of the terminals off the battery. If it dies your alternator isn't working properly. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted June 10, 2007 Share Posted June 10, 2007 Not exactly sure of answers to your questions, but once you get it started pull one of the terminals off the battery. If it dies your alternator isn't working properly. NOT true. if you remove a battery terminal it kills the circuit and the engine will die. on a carbeurated motor you could probably get by with pulling the terminals but on a fuel injected system, all sensors will die and it will no longer run. do yourself a favour and remove your belts (whether serpentine or v-belt), and take your alternator to a rebuild statioin or a place like advance auto and have it tested to see if it's good. if it is, you need to fix your sensor problem because the long starts are killing your battery. also, an alternator is not meant to charge a battery from zero...doing that puts more strain on the internals of an alternator and will result in a short which will severely affect the life of your alternator. charge the battery FULLY, and test the alternator. if the alternator is good and the battery still drains, you have a short in your wiring system which is grounding out and draining it. replace your battery if it won't charge farther than 4, or try to bring it back with some new water and electrolytes. btw, testing your alternator output with a voltmeter won't show an accurate reading...it may show 13 volts but there's a difference between 13 volts and 105 amps...it will show 13 volts on less than an amp and all the way on up, hence you have no way of testing the actual output of the alternator short of bringing it in to be bench tested. that's my .02 and is .02 as passed on to me by many, many brilliant mechanics. Link to comment Share on other sites More sharing options...
DirtyComanche Posted June 10, 2007 Share Posted June 10, 2007 If the alternator works, it should run with the battery pulled after startup. However, with a totally flat battery you cannot bump-start it. Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 11, 2007 Share Posted June 11, 2007 Is having the aux horn wire just hanging out the right thing or does that need to be looped back into the circut some how? (this is the last change I made to the MJ, but that was 12 starts ago) Having the second horn wirs "hanging" is fine, as long as it's insulated. But you had that 2nd horn wire grounded for quite some time, right? I think your current problem might be related to this, as your entire electrical system suffered shorting problems w/o blowing a fuse. Possibly this short caused an additional electrical problem. First thing I would do is have a load test done on your battery. If it checks out okay, you might done some damage to the alt voltage regulator. I'd start there first ............. Link to comment Share on other sites More sharing options...
fiatslug87 Posted June 11, 2007 Share Posted June 11, 2007 Not exactly sure of answers to your questions, but once you get it started pull one of the terminals off the battery. If it dies your alternator isn't working properly. NOT true. if you remove a battery terminal it kills the circuit and the engine will die. on a carbeurated motor you could probably get by with pulling the terminals but on a fuel injected system, all sensors will die and it will no longer run. You are incorrect, I've done this and the motor continues running (on RENIX at least), that's how I diagnosed my bad alternator, replaced it and all was fine. Thanks for the confirmation DirtyComanche. Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted June 11, 2007 Share Posted June 11, 2007 Not exactly sure of answers to your questions, but once you get it started pull one of the terminals off the battery. If it dies your alternator isn't working properly. NOT true. if you remove a battery terminal it kills the circuit and the engine will die. on a carbeurated motor you could probably get by with pulling the terminals but on a fuel injected system, all sensors will die and it will no longer run. I beg to differ, fiatslug87 is correct. This is a age old method of testing an alternator and will for certain tell you if the alt in any MJ is working or not. My alt went in my MJ a couple months back and this worked on my 1989. Batt was fine...bearings in alt shot!! Just about a month ago our WJ LIMITED died in a parking lot. I jumped it and it ran fine. I pulled the batt cable to test it and it stayed running. The factroy batt was shot, easy fix. If it wasn't going to work on any vehicle...it wouldn't have worked on that... There is every gismo jeep ever thought of putting on a jeep on this thing!!! To answer one of your questions... A alt puts out different amounts of current based on RPM and system requirements. (Volt regulator) If you know you need extra "juice", like givign someone a jump. Just kick the idle up. CW Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 I would start by cleaning the terminals and checking the condition of the battery cables. Most of my electrical issues that looked like a battery or alternator problem was simply corrosion or poor contact. I've preached this too. First thing I checked when I popped the hood at the dump. The terminals are clean and the connection looks good. I did notice however the cables are or atleast appear to be facotry originals, so they are probably on their last leg. Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 What I want to know is how much you use the horn to be able to know it wasn't working all the time...? well, once I know I have a problem with something I tend to test it over and over again to make sure its working. Its a bad habit of mine, got it through testing software code. Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 Is having the aux horn wire just hanging out the right thing or does that need to be looped back into the circut some how? (this is the last change I made to the MJ, but that was 12 starts ago) Having the second horn wirs "hanging" is fine, as long as it's insulated. But you had that 2nd horn wire grounded for quite some time, right? I think your current problem might be related to this, as your entire electrical system suffered shorting problems w/o blowing a fuse. Possibly this short caused an additional electrical problem. First thing I would do is have a load test done on your battery. If it checks out okay, you might done some damage to the alt voltage regulator. I'd start there first ............. I can pull the battery and get a load test done at advanced. Definitely the easiest way to start. While I'm there I can pick up another horn to wire into the circut. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted June 11, 2007 Share Posted June 11, 2007 hmm. I will try this on my jeep now. I've only ever done the method on tractors and mostly 6 volts at that soooyea maybe its time that I remove myself from the roots i have planted in that aspect... Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 Not exactly sure of answers to your questions, but once you get it started pull one of the terminals off the battery. If it dies your alternator isn't working properly. i'll definitely do this when I swap in the extra battery I have laying around. I decided to just walk away from it and tear into a bushel of crabs this evening and hang out with friends. I didn't want to be pissed at the MJ all night. Anybody know the answer to Do the 2.5L and 4.0L share the same alternator? Sorry for the multi-post response, I was having a hard time organizing my thoughts into one post. And thanks for all the responses, I really hate trouble shooting electrical problems. Link to comment Share on other sites More sharing options...
CWLONGSHOT Posted June 11, 2007 Share Posted June 11, 2007 While I am unsure if they are the same or not. (I never had both in my hand at the same time to compair) Here is a pic of the one I put in my MJ a couple months back... CW Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 While I am unsure if they are the same or not. (I never had both in my hand at the same time to compair) Here is a pic of the one I put in my MJ a couple months back... CW thanks for the pic. Using the eyeball test they look very similar. I'll have them run the part numbers while I'm in there getting the battery tested tonight. Link to comment Share on other sites More sharing options...
Pete M Posted June 11, 2007 Share Posted June 11, 2007 I would start by cleaning the terminals and checking the condition of the battery cables. Most of my electrical issues that looked like a battery or alternator problem was simply corrosion or poor contact. I've preached this too. First thing I checked when I popped the hood at the dump. The terminals are clean and the connection looks good. I did notice however the cables are or atleast appear to be facotry originals, so they are probably on their last leg. Just trying to cover all the bases, but did you pull them and scrub them good? Just because it looks clean doesn't actually mean squat (and the reverse is true too, buildup of nastiness on the outside doesn't necessarily mean that the connection is affected inside). A good cleaning with a terminal brush can work wonders. :D And if you have any doubt with the cables, replace them! Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 11, 2007 Author Share Posted June 11, 2007 charged the battery all day at work and got it tested at advanced auto. It checked out fine. I cleaned up the terminals and connectors with an official battery terminal cleaner tool then hooked it up. She cranked over no problem. Then I disconnected the positive cable, it near immediately stalled out. Reconnected, started it again, then disconnected the negative, it immediately stalled out. So it looks like I got to get an alternator. :cry: I checked with the parts guys at both napa and advanced. Napa seems to have the better deal, 100amp one for 100 bucks. Looks like thats my project for tomorrow. the real kicker is after I did the comanche testing I did my 3k maintenance on the wrangler. checked the front diff and she came pouring out like metalic water. :eek: bout shait myself. Popped the cover and found a chewed up shim/seal/something :hmm: and all the gear oil was metal flake and had a feeling of water. Not to mention some of the teeth got a new wear pattern. I'm guessing the whatever metal that got chewed up proceeded to break down the fluid. Its impossible that it got contaminated as it was changed 1 month ago to the day and has not been wheeled (I also have outer alloy usa axle seals) ... sorta had a dry may here too. My only guess is I botched my lockrite install, which really surprises me considering this was my second time doing it. So 2 jeeps broken down and bumming a ride to work tomorrow. I'm the complete opposite of happy, with no one to blame but myself. The Mj is an easy fix and will be running tomorrow. Fingers crossed atleast. Link to comment Share on other sites More sharing options...
Pete M Posted June 12, 2007 Share Posted June 12, 2007 Make sure you take the alternator in to have it checked out. It still could be a poor connection at the alternators or something. Link to comment Share on other sites More sharing options...
Oizarod115 Posted June 12, 2007 Share Posted June 12, 2007 when my alternator died it was associated with whining noises and the bearing was REALLY pissed off by the way it sounded. and jeeps take forever to start, if you turn the key two clicks you should hear the fuel pump prime, then crank it, i doubt it's fuel delivery that makes it take a while to crank, the CPS should be replaced if it takes more than a few seconds Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 12, 2007 Author Share Posted June 12, 2007 when my alternator died it was associated with whining noises and the bearing was REALLY pissed off by the way it sounded. My neighbors was the same way in his cherokee. My alternator however isn't really making any noises, just not doing its job. I read that alternators can short out, causing a drain on the system. I checked for shorts in the MJ by putting a test light in line with the negative battery cable and the negative terminal post and it appears the MJ is short free. The light stayed off. and jeeps take forever to start, if you turn the key two clicks you should hear the fuel pump prime, then crank it, i doubt it's fuel delivery that makes it take a while to crank, the CPS should be replaced if it takes more than a few seconds Mine definitely takes more than a few seconds. Usually 5. crank crank, think about giving up, let it crank and it goes. Reason I was thinking it was fuel delivery related was because after a cold start, if you try to get going the MJ will just putter for about 10 secs, getting just a tiny bit of fuel. Then something changes and it starts getting the normal amount of fuel and drives fine. I typically just let it warm up and I don't have that problem. Once it has been driven it will not require a long crank at all, just starts up near immediately. Link to comment Share on other sites More sharing options...
Oizarod115 Posted June 12, 2007 Share Posted June 12, 2007 try priming the pump a few times without starting it then starting it... maybe that'll get you enough fuel up there? Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 13, 2007 Author Share Posted June 13, 2007 got a 100 amp alternator from Napa today and installed it. Went pretty quick, 45 mins total. Had a scare when I first tested the alternator via the same test I used to determine the old one was no good. So start it, disconnect the positive terminal and the truck stalls! Look down, forgot to connect the alternator wires. :oops: :thwak: Plugged it in and now it stays one with the battery disconnected. So I guess that fixes this one for now. The MJ gets DD duty for awhile now that the TJ is at the shop getting looked over, so my fingers will stayed crossed. Link to comment Share on other sites More sharing options...
UNL1MTD Posted June 13, 2007 Author Share Posted June 13, 2007 try priming the pump a few times without starting it then starting it... maybe that'll get you enough fuel up there? do you mean by just turning the key and waiting to hear the pump? I normally do that, no real difference. You mentiond CPS before. Got any reasoning behind that or is that just a 'throw it out there' type guess? Link to comment Share on other sites More sharing options...
Oizarod115 Posted June 13, 2007 Share Posted June 13, 2007 the CPS has to do with spark, and ALOT of times people have startup issues or long crank times its due to the cps so i guess its a standard throw it out there type response ;) (also a royal PITA to change) Link to comment Share on other sites More sharing options...
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